1. Field of the Invention
This invention relates generally to the field of ophthalmology and more particularly to a novel ophthalmic kit and ophthalmic method and instrument for use in implanting a foldable intraocular lens in a patient's eye,
2. Discussion of the Prior Art
The human eye has a crystalline lens situated behind the iris including an outer capsule attached by zonules to the ciliary muscle of the eye and a crystalline matrix filling the capsule. The lens capsule has anterior and posterior membrane-like walls referred to as anterior and posterior capsules, respectively. In a normal eye, the lens is optically clear. Light rays entering the eye through its cornea and iris pass through the lens to the retina of the eye, and the lens is automatically shaped by brain control of the ciliary muscle to focus these incoming light rays on the retina.
The human eye is subject to a variety of abnormal conditions that degrade or totally destroy proper optical functioning of the eye. One of the more common of these conditions is known as a cataract and involves clouding of the crystalline lens matrix which obstructs or blocks passage of light rays through the lens to the retina. Simply stated, the ophthalmic procedure for curing a cataract involves extraction of the cataractous natural lens through an incision in the eye and implantation of an artificial intraocular lens in the eye through the incision.
In the early days of such cataract surgery, the entire cataractous natural lens was removed by a surgical procedure known as intra-capsular lens extraction. While this procedure is occasionally used today in certain circumstances, it has many disadvantages among the more serious of which is the need to make a relatively large incision in the eye to permit removal of the natural lens through the incision.
These disadvantages of intra-capsular lens extraction led to the development in the 1970's of an improved procedure for removing a cataractous natural lens. This improved procedure, known as extra-capsular extraction, involves removal of only the anterior capsule or a central portion of the anterior capsule of the natural lens, phacoemulsification of the cataractous natural lens matrix, and aspiration of the emulsified matrix. This extra-capsular extraction procedure with phacoemulsification requires only a relatively small incision on the order of 3 mm in length and thereby reduces or eliminates many of the risks associated with intra-capsular lens extraction.
It was not until the development of the foldable intraocular lens in 1986, however, that the small incision advantage of extra-capsular lens extraction with phacoemulsification could be utilized. This was due to the fact that up until 1986, the only available intraocular lenses were herd lenses which required an incision on the order of 6-8 mm in length for insertion into the eye. Accordingly, even though the natural lens was extracted through a 3 mm incision, the surgeon had to enlarge the incision to 6-8 mm in order to insert the hard intraocular lens into the eye.
A foldable intraocular lens has a normal unfolded lens configuration in which the lens is conditioned to perform its intraocular lens function. The lens is foldable to a compact folded configuration for insertion into the eye through a small incision, such as the 3 mm incision required by extracapsular lens extraction with phacoemulsification. In its folded configuration, the lens stores elastic strain energy which unfolds the lens to its normal lens configuration when it is released within the eye.
A variety of foldable intraocular lenses and instruments for inserting such lenses into the eye have been developed over the period from 1986 to the present. Among the patents disclosing such lenses and instruments are the following:
U.S. Pat. No. 4,575,998 dated Mar. 4, 1986, to Mazzocco discloses (FIGS. 31-61) a variety of foldable intraocular lenses and instruments for inserting the lenses into the eye including instruments having a pair of opposing jaws which are closed about a foldable lens (FIGS. 52, 54).
U.S. Pat. No. 4,681,102 dated Jul. 21, 1987, to Bartell discloses a foldable lens insertion instrument including a load chamber which is closable longitudinally about a foldable intraocular lens to fold the lens and insertable into a lens insertion device including a plunger movable forwardly through the insertion device and load chamber to push the folded lens through the anterior tip of the device into the eye.
U.S. Pat. No. 4,715,373 dated Dec. 29, 1987, to Mazzocco et al discloses an instrument having a pair of jaws for gripping a foldable intraocular lens in its folded configuration, a sleeve for surrounding the jaws to hold them in their closed positions, and means for releasing the folded lens from the instrument into the eye.
U.S. Pat. No. 4,765,329 dated Aug. 23, 1988, to Cumming discloses a sterile ophthalmic package or kit containing a tube for holding a foldable intraocular lens and having a slender anterior tip for insertion into the eye, and a probe for pushing the lens from the tube, through the tip, into the eye.
U.S. Pat. No. 4,862,885 dated Sep. 5, 1989, to Cumming discloses a sterile ophthalmic package or kit including a tray holding a disposable lens insertion device having a pair of open lens gripping jaws straddling an unfolded deformable intraocular lens supported on the tray with the length of the lens extending lengthwise of the jaws, means on the tray for closing the ,jaws about the lens to fold and grip the lens in its folded configuration, and a handle including means for holding the jaws closed and pushing the folded lens from the jaws into the eye following removal of the instrument and lens from the tray and insertion of the jaws of the insertion device into the eye.
U.S. Pat. No. 4,934,363 dated Jun. 19, 1990, to Smith discloses an ophthalmic instrument having a disposable insertion device including a tube insertable into the eye and containing a movable lens holder, a reusable handle removably mounting the insertion device including means for moving the lens holder back and forth in the tube of the insertion device to first draw a foldable lens into the tube and thereby fold the lens and thereafter eject the folded lens from the tube into the eye.
U.S. Pat. No. 4,976,716 dated Dec. 11, 1990, to Cumming discloses a sterile ophthalmic package or kit including a tray holding a disposable lens insertion device having a pair of open lens gripping jaws straddling an unfolded deformable intraocular lens supported on the tray with the length of the lens extending lengthwise of the jaws, means on the tray for closing the jaws about the lens to fold and grip the lens in its folded configuration, and a reusable handle for holding the jaws closed and including a plunger for pushing the folded lens from the insertion device into the eye following removal of the instrument and lens from the tray and insertion of the jaws of the insertion device into the eye.